Machine tools of this type, hereinafter for short "boring tools", for metallic or plastic workpieces are well known. They usually comprise a tool body on which a plurality of cutter chips are located. To secure the cutter chips to the tool body, the cutter chips have a hole through which a clamping bolt is passed. For positive positioning of the cutter bits, it has previously been proposed to utilize chip holder plates which are inserted in the tool body, the cutter bits then being secured to the chip holder plate. The chip holder plates, themselves, are screw-connected to the tool body. The cutter bits are so arranged on the tool body that their cutting range overlaps. The radially outermost cutter bit has a cutting corner which defines the maximum diameter of the hole being drilled or bored. The radially innermost cutter bit has a cutting edge which extends beyond the axis of the workpiece.
Boring tools of this type have been described in German Utility Model Publication DE-GM No. 70 24 898. Placing the cutter chips on separate chip holding plates protects the tool holding body if the cutter chips should become damaged. The chip holding plates, of course, being small elements are readily replaceable and much less expensive than the tool body. The tool holding plates can be made in various forms and are usually different in different types of boring tools. They may be semicylindrical or in the form of a circular segmental plate. Stocking different chip holder plates requires substantial storage space and inventory. It has been customary to make boring tools to size for particular diameters which, in turn, requires chip holder plates associated with specific boring tools of specific diameters, further increasing the inventory and storage problems since, practically for every different diameter, a separate tool body was necessary and, for each separate tool body, the holder plates has to be made and stored.